The Optiplex 7020 is the client from which you accessing your server, correct? What OS is running on this client?
The Permission denied error you are getting is usually related to you not having the correct permissions to execute the command. Make sure you are following the correct guide specific to the OS on your client device carefully without skipping any steps.
Running Linux Mint Cinnamon. I did carefully follow the instructions. Everything seemed to work correctly until I got to the sudo bash -c aqua-educator.crt >> /etc/ca-certificates.conf command.
Glad you got it working! Please post what you determined to be the problem, as I’m sure others may find it useful in the future. It also helps us identify possibly unclear parts of the guide.
I never did get the cert to be recognized by either Chrome or Firefox, but was able to log in securely with my Vivaldi browser. (I’m running Linux Mint)
Thanks!